Mate in 4 opening challenge

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shadowpeaa

White to play to mate in four moves from starting position.
Black have to copy whatever white does.
White cannot make checks if black cannot copy legally

shadowpeaa
.
Mr_Alex_Pims
Hard
Deranged

Can someone please confirm that this puzzle is even possible?

I've spent ages trying and the best I can come up with is a mate in 7.

Mr_Alex_Pims
Yes
R5M8

 

R5M8

Found another one: